Cementing is used in the oil and gas industry to seal off fluids and unconsolidated materials from entering the well bore, for packing off unwanted zones, as a loss circulation material and to abandon wells.
Current cementing technology requires a casing or liner to be placed in the well bore and a cement slurry is then pumped downhole and back up into the space or annulus between the casing or liner and the wall of the well bore. However, each succeeding casing or liner placed in the wellbore has an outside diameter significantly reduced in size when compared to the casing or liner previously installed. Thus, each time casing is run in a wellbore the diameter of the wellbore is reduced by the size of that casing.
Further, where operations require the cementing of casing such as the setting of surface or production casing, there is the need to use the following equipment: a casing shoe, float equipment and cement plug. This equipment can only be removed by drilling them out. This takes up valuable drilling time and can prove difficult when using a reverse circulation concentric drill string system.
The present invention allows the cementing operation to be completed without the need to run casing or have cement returned to surface thereby allowing larger diameter wellbores to be drilled into zones of interest. Further, time and money are saved on not having to run intermediate casing strings, and cement does not have to be pumped to surface. Finally, the present invention allows cementing to be completed without having to drill out equipment such as cement plugs, float equipment and casing shoes.